Magnetic disk devices apply error checking and correcting (ECC) to the read data read from disks. For example, magnetic disk devices perform a decoding process for the read data, using a low density parity check (LDPC). Magnetic disk devices may repeatedly perform a decoding process over and over again for data (error data) which failed in a decoding process. In this case, the magnetic disk devices perform a process (out-of-order execution) for transmitting data having no error to a buffer memory before the error data. Recently, in the out-of-order execution of magnetic disk devices, the time (latency) until error data is transmitted to a buffer memory has been increased.